Shelf conveyors that move vertically within a casing between transferring stations that have transferring openings are well known, but there are considerable problems with respect to improperly transferred articles that may jam between an upwardly moving shelf and the casing, improperly removed articles from a downwardly moving shelf that may remain long enough to be jammed by the next downwardly moving shelf, and operation of a conveyor in the wrong direction to jam an article on a transferred device by a downwardly moving shelf when in fact shelves should be moving upwardly to pick up the article from the transfer device. Further, transfer devices with abutment arms have assembly and adjustment difficulties with respect to the various transfer positions and storage positions when they are not needed.